COMBINATION SMOKE/CO ALARMS are UL listed with voice identification, accompanied by an 85 db alarm. Voice system states "FIRE!FIRE!" when smoke is detected and "WARNING! CARBON MONOXIDE!" when CO is detected. Test/Reset button allows testing of both smoke and CO sensors. Warning light indicates low battery levels on COSM. Batteries included. NOTE: The smoke alarm takes precedence when both smoke and carbon monoxide are detected.